Self-assembled film containing the rare earth (RE) elements was formed on a silicon dioxide substrate, in order to reduce the surface adhesion and the f riction force of micro electro-mechanical systems (MEMS). The film thickness was measured as 2nm. The tribological experiment result shows that the friction coefficient of SiO2 substrate reduces from 0.5 to 0.1 after the formation of RE self-assembled film on its surface. Besides, RE self-assembled film exhibits a high wear resistant ance.

Three types of surface modifiers, N-β-aminoethyl-y[1]-aminopropyltrimethoxysilane coupling agent (SGS), a mixture of silane and rare earth elements (SGS/RES), and rare earth elements surface modifier (RES), were used to treat the glass fiber surface. Tensile tests of glass fiber–reinforced polytetrafluoroethylene (GF/PTFE) composites with different surface treatment conditions, surface modifiers, and glass fiber content were carried out. Finally, the fracture surface morphologies of GF/PTFE composites were investigated using scanning electron microscopy. Experimental results showthat the tensile properties of the treated GF/PTFE composite increased compared with those of the untreated one. RES is superior to SGS/RES and SGS modifiers in promoting interfacial adhesion between the glass fiber and PTFE because of the effects of rare earth elements on the compatibility. Meanwhile, the optimum contents of rare earth elements for the improvement of the tensile properties of GF/PTFE composite were obtained for RES and SGS/RES modifiers. The interfacial adhesion of the GF/ PTFE composites treated with RES or SGS/RES modifiers was mainly controlled by the contents of rare earth elements. The tensile properties of the GF/PTFE composites improved considerably when the content of rare earth elements in surface modifiers was 0.2-0.4wt%, and the optimumtensile performance of GF/PTFE composites was obtained at 0.3wt% RE content.

Effect of rare earth elements (RE) on erosion resistance of nitrocarburized layer of 38CrMoAl steel was investigated. The results indicate that significant improvement occurs in erosion resistance of nitrocarburized 38CrMoAl steel by introducing RE during nitrocarburizing processing as compared with conventional nitrocarburizing processing. Results of mechanical testing show that both hardness and impact toughness of RE-nitrocarburizing layer of 38CrMoAl steel increase as compared with the conventional one. Optical microscopy reveals that there is improvement in the nitrocarburized layer attributed to the introduction of RE, which results in improvement in erosion resistance. Surface morphology observation of tested samples reveals that predominantly furrow2like peelings from plastic deformation are observed for RE nitrocarburizied 38CrMoAl steel, while the furrow-like peeling with initial cross crack and large grinding peelings were observed for conventionally nitrocarburized samples.

An investigation of the effect of rare earth elements (RE) on erosion resistance of nitrided 40Cr steel is carried out using an erosion test rig in a water-based slurry with quartz particles. Results indicate that a significant improvement occurs in erosion resistance of nitrided 40Cr steel by introducing RE in nitriding processes comparing conventional nitriding processes. Measurement of physical properties exhibits that both hardness and toughness of nitrided 40Cr steel increase in the case using RE-nitriding processes comparing the conventional. Metallurgical microscopy reveals that there is a transformation from a coarse to a fine metallurgical microstructure in the case and an increase in the thickness of white layer on the top of case attributed to an introduction of RE in nitriding, which attributed to an improvement in erosion resistance and physical properties. EDX analysis shows that RE diffuse into the case of 40Cr steel in nitriding process as a result of appearance of micro-alloy. Microscopy revealed that the furrow-like peeling from plastic deformation of material is predominant erosion mechanism of RE nitrided 40Cr steel while the furrow-like peeling with initial cross crack and large grinding peelings takes place predominantly in tests of conventionally-nitrided ones, which results in a significant difference in erosion resistance.